Employee Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Defined contribution plan recognized expenses		$ 2,800	$ 2,800	$ 3,900
Deferred compensation, retirement age		65 years
Deferred compensation requisite service period		10 years
Deferred compensation recorded liability	$ 300	$ 300
Cash surrender value of life insurance	3,200	3,200
Proceeds from life insurance policy	1,900	$ 1,861	0	0
Maximum
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Age older but less than		65 years
Retiree medical plan
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Deferred compensation requisite service period		10 years
Unfunded liability	$ 900	$ 900	1,100
Retiree medical plan | Minimum
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Age older but less than		55 years
Retiree medical plan | Maximum
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Net periodic postretirement benefit cost (less than)		$ 100	$ 100	$ 100
Deferred compensation plan
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Percentage of employee based salary permitted for deferral under the plan	50.00%	50.00%
Percentage of employee annual bonus permitted for deferral under the plan	100.00%	100.00%
Deferred compensation expense adjustment (less than)		$ 100
Deferred compensation plan assets	$ 6,800	6,800
Deferred compensation plan | Company owned life insurance policies
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Deferred compensation plan assets	$ 6,700	$ 6,700